1,721,136 research outputs found
Ozone isotopologue measurements from the Atmospheric Chemistry Experiment (ACE)
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Previous issue date: 2019-06-20Made available in DSpace on 2020-01-25T19:30:02Z (GMT). No. of bitstreams: 4
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Previous issue date: 2019-06-20Near global ozone isotopologue distributions have been determined from infrared solar occultation measurements of the Atmospheric Chemistry Experiment (ACE) satellite mission. ACE measurements are made with a high resolution Fourier transform spectrometer. Annual and seasonal latitudinal fractionation ( value) distributions of the ozone isotopologues OOO, OOO and OOO were obtained. Asymmetric ozone (OOO) shows higher fractionation compared to symmetric ozone (OOO). The maximum ozone fractionation occurs in the tropical stratosphere as expected. An enhancement of the heavy ozone isotopologues is also seen in the Antarctic polar vortex
High temperature methane line broadening by H2
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Previous issue date: 2019-06-21Made available in DSpace on 2020-01-25T19:30:02Z (GMT). No. of bitstreams: 5
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Previous issue date: 2019-06-21Absorption spectra of hot methane were recorded in the 2300-3200 cm spectral region ( mode) using a Bruker 120/125 HR Fourier transform spectrometer. Methane was heated in a quartz cell in a tube furnace at 295, 473, 673, 873 and 1073 K. Line broadening of the methane spectra was investigated by adding 50, 150 and 400 Torr of H as a broadening gas to 0.5 Torr of methane. A preliminary spectral fit of the methane data was performed using Voigt line shape functions with the WSpectra program. The temperature and pressure dependence of the line broadening parameters were studied; additional spectra are needed for more temperatures and pressures. A more sophisticated analysis using non-Voigt line shapes and a multi-spectral fit will be carried out
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Laser spectroscopy of calcium monohydroxide and calcium monodeuteroxide
No full textCaOH and CaOD were studied in the gas phase using dye laser spectroscopy. The molecules were produced in a Broida-type oven. Laser excitation spectroscopy was used to study the Ḃ²Σ⁺-X²Σ⁺ transition of CaOD near 5500 Å. The 000-000 band was rotationally analyzed and r₀ structures were established for both states. Like other alkaline earth monohydroxides, CaOD is a linear molecule. For the Ḃ²Σ⁺ state the following bond lengths were found: r(Ca-O) = 1.9697Å and r(O-H) = 0.9179Å, while for the X²Σ⁺ state, r(Ca-O) = 1.9849 and r(O-H) = 0.9207Å. Optical-optical double resonance (OODR) was used to investigate the upper electronic states of CaOH. A ²Π electronic state and three ²Σ vibronic states were observed for the first time in the region 2990 - 3070 Å. For the ²Π state the rotational constant, B°, and the band origin energy, T₀, were calculated: B° = 0.347 cm⁻¹ and T = 32360 cm⁻¹
Line lists for LiF and LiCl in the X1Σ+ state
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Previous issue date: 6Made available in DSpace on 2018-01-29T23:03:25Z (GMT). No. of bitstreams: 3
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Previous issue date: 6Alkali-containing molecules are expected to be present in the atmospheres of exoplanets such as rocky super-Earthsfootnote{Phil. Trans. R. Soc. A textbf{372}, 20130087 (2014)} as well as in cool dwarf stars.footnote{Astrophys. J. textbf{519}, 793 (1999)} Line lists for LiF and LiCl in their textit{X} ground states have been calculated using LeRoy’s LEVEL program.footnote{J. Quant. Spectrosc. Radiat. Transfer textbf{186}, 167 (2017)} The potential energy functions, including the effects of the breakdown of the Born-Oppenheimer approximation, are obtained by direct fitting the experimental infrared vibration-rotation and microwave pure rotation data with extended Morse oscillator potentials using LeRoy’s dPotFit program.footnote{J. Quant. Spectrosc. Radiat. Transfer textbf{186}, 179 (2017)} The transition dipole matrix elements and line intensities were obtained with LEVEL using a dipole moment function from a high level textit{ab initio} calculation
Visible Opacity Of M Dwarfs And Hot Jupiters: The Tio B3π- X3∆ Band System
Full text linkThe TiO B- X electronic transition ( system) is an important opacity source in the atmospheres of M dwarfs and hot Jupiter exoplanets. The 0–0, 1–0, and 2–1 bands of the B- X band system have been analyzed using a TiO emission spectrum recorded at the McMath-Pierce Solar Telescope, operated by the National Solar Observatory at Kitt Peak, Arizona. Improved spectroscopic and equilibrium constants were determined. Line strengths were calculated from an \textit{ab initio} transition dipole moment function scaled using an experimental lifetime. A new line list for v = 0-2 and v= 0-4 of the B- X band system is provided
A Local Mode Study Of Pseudorotational Effects In The Infrared Spectra Of The Scissor And Ch Stretch Vibrations Of Cyclopentane
Full text linkWe report and interpret recently recorded high resolution infrared spectra for the fundamentals of the CH scissors and CH stretches at -50 C of gas phase cyclopentane. We extend previous theoretical studies of this molecule, which is known to undergo barierless pseudorotation, by constructing local mode Hamiltonians of the stretching and scissor vibrations for which the frequencies, couplings, and linear dipoles are calculated as functions of the pseudorotation angle using B3LYP/6-311++(d,p) and MP2/cc-pvtz levels of theory. Symmetrization () of the vibrational basis sets leads to simple vibration/pseudorotation Hamiltonians whose solutions lead to good agreement with experiment at medium resolution, but which miss interesting line fractionation when compared to the high resolution spectra. In contrast to the scissor motion, pseudorotation leads to significant state mixing of the CH stretches which themselves are Fermi coupled to the scissor overtones
A new linelist for OH A2Σ-X2Π electronic transition
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Previous issue date: 6The OH radical is observed in cool stars, interstellar medium, comets and is an important oxidizer in the Earth’s atmosphere. A new linelist for the (A -X ) transition of OH has been calculated. The line positions have been obtained from the literature and the line intensities were calculated from a new ab initio transition dipole moment function obtained from Molpro quantum chemistry package. This dipole moment function along with the RKR potentials have been used in LeRoy’s LEVEL program in order to calculate transition dipole matrix elements. These matrix elements are transformed from Hund’s case (b) to Hund’s case (a) as required for Western’s PGopher program. The linelist was calculated with PGopher
High Temperature Fourier Transform Spectroscopy Of The B <sup>1</sup>Π - X <sup>1</sup>Σ<sup>+</sup> Transition Of Zro
No full textS-type stars are characterized by the presence of ZrO electronic transitions. Analysis of several ZrO band systems has, to date, relied upon data collected using photographic plates and has escaped a more modern spectral analysis made possible with programs such as PGOPHER. We present a re-analysis of a number of vibrational bands associated with the B - X transition based on a high resolution (0.04 cm) Fourier transform emission spectrum collected at the National Solar Observatory by S. Davis. The ZrO source was a carbon tube furnace at 2390 K. Updated spectroscopic constants are presented and discussed.Made available in DSpace on 2021-09-24T21:09:07Z (GMT). No. of bitstreams: 2
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Previous issue date: 2021-06-23Made available in DSpace on 2022-01-21T16:10:28Z (GMT). No. of bitstreams: 4
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Previous issue date: 2021-06-2
Identifying Titan’s atmosphere – A look at hydrocarbons potentially present in the atmosphere of Saturn’s most interesting moon
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Previous issue date: 2019-06-19Made available in DSpace on 2020-01-25T19:29:48Z (GMT). No. of bitstreams: 4
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Previous issue date: 2019-06-19Much research in planetary atmospheres is focused on Titan, one of Saturn’s moons. This interest is driven by the Cassini-Hyugens mission and the fact that Titan’s atmosphere is considered a potential analog of prebiotic Earth. In order to identify the chemical composition of the moon’s atmosphere a catalog of known spectra is needed for accurate comparisons. The molecules of interest are small hydrocarbons, as they have been observed on Titan and can be generated via photochemistry of methane, a primary component of Titan’s atmosphere. This talk will look at propane, as well as new data that will be recorded for some of the larger possible hydrocarbons, such as neopentane, a molecule for which there is little data in the literature, and n-butane. Absorption cross sections were obtained for pure samples of propane and with hydrogen and helium broadening gases to simulate astronomical environments. The propane spectra were taken in the 3 micron region, at temperatures ranging from 200 to 298 K and at broadening gas pressures from 0 Torr to 300 Torr. Calibration of the cross sections were carried out using data from the Pacific Northwest National Laboratory (PNNL) infrared database
Spectroscopy of TiO singlet states
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Previous issue date: 6Made available in DSpace on 2018-12-12T22:36:20Z (GMT). No. of bitstreams: 4
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Previous issue date: 6TiO is a molecule of considerable astronomical importance. It is present in the atmospheres of oxygen-rich lowmass stellar objects. Three Fourier transform emission spectra have been used to determine improved and consistent spectroscopic constants of the a1∆, b1Π, d1Σ +, c1Φ and f1∆ states of TiO by fitting the b1Π-a1∆, b1Π- d1Σ +, c1Φ-a1∆ and f1∆-a1∆ systems. This analysis provides the most extensive fit of the TiO singlet states. New bands of the b1Π-a1∆ and c1Φ-a1∆ systems have been measured and an extensive list of line positions will be published
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